1. Field of the Disclosure
This disclosure relates in general to a process for the separation of hydrogen fluoride from fluoroolefins by extraction. In particular, the process for separation of hydrogen fluoride from fluoroolefins comprises liquid-liquid extraction
2. Description of the Related Art
The chemical manufacture of fluoroolefins often produces mixtures of the desired fluoroolefins and hydrogen fluoride (HF). The separation of fluoroolefins from these mixtures is not always easily accomplished because many fluoroolefins form an azeotrope with HF. Existing methods of distillation and decantation are very often ineffective for the separation of these compounds. Aqueous scrubbing may be effective, but requires the use of large amounts of scrubbing solutions and produces excessive waste and a wet product that must then be dried.
WO 98/00379 discloses the use of sulfuric acid as extractant to separate HF from a fluorocarbon (e.g. HFC-245fa or HFC-356mcfq) by preferentially extracting the HF into the sulfuric acid phase. WO 98/00380 discloses a similar extraction process utilizing water to preferentially extract the HF. US 2001/0004961 A1 discloses the use of hydrocarbon and halocarbon solvents to remove HF from mixtures with hydrofluoroalkanes of formula CaH(2a+2)−bFb, wherein a=3 to 6 and b=1 to 2a+1, by liquid-liquid extraction.
Some fluoroolefins have been found to form azeotropes with hydrogen fluoride, complicating their separation. Aqueous and caustic scrubbing can be effective, but the valuable HF is converted to a waste and additional equipment is needed to dry the wet fluoroolefin produced. Therefore, there is a need for new methods of separating fluoroolefins from HF.